Is 3.2.2 Cas 2, or is 2.2.2 Cas2?

[erikiksaz]

i've been hearing lots of crap about "true" cas 2 and all this other weird stuff. so what is the cas 2 that most tweakers and overclockers want? right now in my rig, it seems that i have 3.2.2 cas sticks in there, is that cas2?

 

[Robor]

I'm not positive but I think CAS 2 is 2-2-2. I know the good stuff is 2-2-2 anyway.

Rob

 

[compuwiz1]

Cas 2 can be 2-3-3, but can you force it all to 2-2-2? If so then your ram will run there. True CL2 will default to that by the SPD chip on board, but much of the good ram out there will still run at CL2, or even better 2-2-2, even though the SPD is programmed to CL3.

It must be a cost thing, but even though the Infineon on my site is a CL3 SPD, it almost always runs 2-2-2. I can't get them to make it for me with a default of CL2.

 

[erikiksaz]

yeah, i've noticed the "good" stuff is 2.2.2. i just visited compuwiz's site, and he has 3.2.2 ram, but it's also called cas2. so all these damn numbers get confusing. does anyone know if crucial's cas2 ram is really 2.2.2?

 

[compuwiz1]

Erik, crucial makes true CL2 ram. It has nothing to do with whether the chips will actually run at 2-2-2, but back to the SPD used. The Infineon on my site does 2-2-2 @ PC133, no problem, and most likely 2-2-2 @ PC150, but we are conservative. Personally, I get better results with Infineon, than with Micron.

 

[Anaconda]

if i want to maxime my memory performance, how should i set my memory timings or whatever. i can only go up to 133 fsb with my fic ad11

 

[Salvador]

Where can you find this 2-2-2? Is it on the stick of RAM?

Thanks,

Sal

 

[erikiksaz]

well, i found out one place that shows the 2.2.2 and such is in sandra. although this is only if spd is disabled, and you set the settings manually. hey comp, if i set the bios to "control by spd," with crucial ram, i should be getting 2.2.2 right?

 

[smp]

If your crucial is 'true' cas2 then yes.

Salvador: No, it won't be written on the stick (at least usually).. but if you go in your bios, you can find the RAM settings for CAS, RAS to CAS, and another one. When people say 2-2-2 they mean that all three of those are set to 2. "True" cas 2 ram, defaults to that... because, like Compuwiz noted, there is a chip (the spd) on the PCB of the ram that tells the bios to default to that. When you buy soemthing like infineon or micron, it's SPD tells your bios to default to 3-3-3 (which is conservative and should always work) .. you can just go in and turn of "set to SPD" and then you can change them all to 2-2-2 .. or 3-2-2 or whatever combination posts and is stable. Cas 2 vs. Cas 3 at 133mhz is almost as big a performance hit as 133 to 100.. so keep that in mind. Cas 2 is way better.

 

[thermite88]

CL or CAS latency is the amount of time in nanoseconds or clock cycles between a request to read the memory, and when it is actually output. SDRAMs are typically referred to as CL2 or CL3, with CL2 parts being faster, from the same manufacturer.

The user, i.e. you, selects the CL in the motherboard BIOS. If the SDRAM is fast enough, it will run stable in CL2. Most of today's SDRAM comes with a EEPROM call SDP (Serial Presence Detect). The SDRAM module manufacturer load the timing information into this SPD ROM. The user can allow the motherboard to read the SPD and set the timing or CL accordingly. The user override the SPD settings when he wants to overclock.

Therefore, the user can find out what the SPD timing recommendation is by allowing the SPD to set the CAS latency. Some manufacturer, such as KingMax, publishes the SPD content in their specification sheet. There are also utility program that dump the SPD contect. SANDRA's commercial version comes with a SPD read module, SPDINFO.EXE.

The SDRAM module manufacturer or their service department can easily re-program the SDP (an EEPROM). Infineon uses 7.5 ns chips in their CL3 SDRAM. Crucial uses 7.5 ns chips in both of their CL2 and CL3 SDRAM. In most cases, the Infineon module can be pushed to higher overclock FSB at CL2.

 

[Salvador]

Thanks for the lessons guys. What I'm after actually is what I need to change in my BIOS to make sure the RAM is running at its fastest.

BTW.. I have Cas2 Crucial.

Sal

 

[Salvador]

I just went into my BIOS and these are my settings:

SDRAM PH Limit: 32 cycles
SDRAM Idle Cycle Limit: 8 cycles
SDRAM TRC Bank Cycle Time: 8 cycles
SDRAM TRP SRAS Precharge: 3 cycles
SDRAM TRAS Timing: 5 cycles

** Changed both of these to 2 from 3 after installing 256 mb's of PC133 Cas2 RAM.**
vvvvvvvvvvvvvvv
SDRAM CAS Latency: 2 cycles (was 3)
SDRAM TRCD Timing: 2 cycles (was 3)
^^^^^^^^^^^^^^^

Are these the correct settings? Can somethign else be changed to give me the full potential of the better RAM?

Thanks again,

Sal

 

[EricHagen]

The numbers mean...


CAS-RAS-CAStoRAS

2-3-3 is

CAS latency 2
RAS latency 3
CAS-to-RAS latency 3

CAS is essential.
the other settings tend to have a much smaller impact on performance because memory spends more time waiting for Column Access Strobe (CAS) than it does Row Access Strobe.

Eric

 

[erikiksaz]

<CAS is essential.
the other settings tend to have a much smaller impact on performance because memory spends more time waiting for Column Access Strobe (CAS) than it does Row Access Strobe>


thanks a LOT, that was helpful.

 

[Salvador]

Ok.. I got CAS, but what is RAS and the CAS-to-RAS from what I posted?

Is the RAS the SDRAM TRP SRAS Precharge? What should this be set to? 2?

What is the CAS-to-RAS from what I posted?

Thanks again,

Sal

 

[Expandable]

Thanks for a good info guys.